The present invention relates to a walk assisting apparatus which provides means for unassisted walking to a person having difficulty walking, such as from leg paralysis or other conditions.
The conventionally used walk assisting apparatus to be put on a person having difficulty walking who has sense paralysis or muscular function loss of both legs or the lower trunk due to damage to the medulla spinalis, is for a "large swing walk" in which the coxae are fixed, and both legs are simultaneously swung forward with the body weight born on crutches. However, this walk requires a wearer to consume very much energy, which makes it difficult for the wearer to walk long distances.
In view of this, walk assisting apparatuses which enable the "alternate walk," made by a normal person by alternately putting forward the left and the right legs, has been proposed. A problem with the conventional walk assisting apparatuses is that both leg supports have the same length, and when a wearer swings forward one leg, the sole of the leg is caught by the ground, which hinders the forward swing of the leg unless he much tilts the body. Accordingly, he is forced to walk forward, alternately tilting the body left and then right, which consumes his energy and destabilizes his walk.
A walk assisting apparatus has been proposed in which, by means of a gas pressure-type support length changing mechanism, a pair of the left and the right leg supports for fixing the legs of a wearer have support lengths extended and retracted in accordance with walking motions of the wearer so that one of the leg supports alternately becomes longer than the other. This walk assisting apparatus makes it necessary for a wearer to much tilt the body alternately left and right to walk, and makes it impossible for the wearer to stably make the alternate walk with relatively small energy consumption.
Here, in such alternate walk, when a wearer puts one of the legs forward, the other leg is left behind with respect to the body. The normal person unconsciously makes this motion. However, when a person having a walking difficulty makes the alternate walk, it is necessary that the legs are forcedly put forward alternately while the legs are interlocked with each other so that when one of the legs is put forward, the other is forcedly retreated.
An interlocking mechanism of full length walking braces for both legs of such walk assisting apparatus typically comprises, as exemplified in FIG. 15, interlocking shafts 109 mounted on rear parts of a trunk brace 102 by shafts and extended horizontally, and having a clutch 115 interposed between the interlocking shafts 109; first link members 101L, 101R having one end secured respectively to one end of the interlocking shafts 108 and extended in opposite direction to each other and normally to the interlocking shafts 109, and second link members 103L, 103R interconnecting the other ends of the first link members and leg supports 104L, 104R at points far below coxae 103L, 103R. The four-link mechanism constituted by the first and the second link members, the leg supports and the trunk brace 102 is interlocked by the interlocking shafts 109 so that when a wearer swings one leg forward, the other leg is retreated (see, e.g., Japanese Patent Laid-Open Publication No. 114089/1984).
However, the full length walking braces for both legs including such a conventional interlocking mechanism requires higher rigidity so that a person having difficulty walking can make the alternate walk motion as a normal person does. Higher rigidity adds weight to the brace, however, which gives a greater physical load to the person having difficulty walking.
As means for increasing the rigidity, a walk assisting apparatus includes full length walking braces for both legs which are mounted on a single shaft at an upper part inside the apparatus. However, in this walk assisting apparatus, the center of swing of the left and the right braces is positioned far remote from the physiological swing center of the coxae, which makes the normal alternate walk impossible. In the case where a trunk brace is necessary for a wearer having trouble in the upper spinal cord, an outside coxa link is provided, and the positions of the rotation axes of the inside shaft and of the outside link are much deflected from each other. As a result, a smooth walk is quite impossible, so that this type of walk assisting apparatus is applicable to restricted spinal cord damages.